Technological development and increasing demand for mobile devices have led to a rapid increase in the demand for secondary batteries as an energy source, and nickel-cadmium batteries or hydrogen-ion batteries have been used as conventional secondary batteries, but recently, lithium secondary batteries have been widely used due to their very low self-discharge rate, high energy density, and free charging/discharging since a memory effect does not substantially occur in comparison to nickel-based secondary batteries.
Such a lithium secondary battery mainly uses lithium-based oxide and a carbon material as a cathode active material and an anode active material, respectively. The lithium secondary battery includes an electrode assembly, which includes a cathode plate coated with the cathode active material, an anode plate coated with the anode active material, and a separator disposed therebetween, and an outer casing, i.e., a battery case, to accommodate with a hermetic seal, the electrode assembly therein along with an electrolyte solution.
A lithium secondary battery includes a cathode, an anode, and a separator and an electrolyte that are disposed therebetween, and is classified into a lithium-ion battery (LIB) and a polymer lithium-ion battery (PLIB) depending on materials used for a cathode active material and an anode active material. Typically, an electrode of a lithium secondary battery is formed by applying a cathode active material or an anode active material to a current collector such as an aluminum or copper sheet, a mesh, a film, foil, etc.
Meanwhile, in the lithium secondary battery, a swelling phenomenon of expansion and shrink of a secondary battery may repeatedly occur due to gas generated in charging and discharging of the secondary battery, and due to the repeated occurrence of the swelling phenomenon, deformation occurs in a battery module and a mounting portion may be damaged.